Pavements & Structures TEST METHOD WA 220.1

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LOS ANGELES ABRASION VALUE

SCOPE This method describes the procedure for the determination of the Los Angeles Abrasion Value of aggregate. APPARATUS 1. Australian Standard sieves (Grade B) as required. 2. A thermostatically controlled oven with good air ventilation capable of maintaining a

temperature within the range of 105°C to 110°C. 3. Sieve brushes. 4. Balance readable and accurate to at least one gram. 5. Sample divider of the multiple slot type. A suitable design is shown in Figure 1. 6. Los Angeles Machine essential dimensions complying with Figure 2. 7. Worksheet, MRD 1165 (recommendation only). PROCEDURE 1. Obtain a test sample taken in accordance with Test Method WA200.1. 2. Select a grading defined in Table 1 appropriate to the particle size distribution of the test

sample. 3. Wash the test sample by agitation under running water for approximately ten minutes. 4. Dry the test sample to constant mass (Note a), in an oven at a temperature within the

range of 105°C to 110°C, cool to room temperature and sieve it on the appropriate sieves until a sufficient mass of each fraction has been obtained. Adjust the mass of material so obtained for each sieve fraction by quartering or riffling, if necessary, to within two percent of the relevant mass shown in Table. 1. Determine the mass of each fraction and combine the sieve fractions to form a test portion.

5. Record the mass (m1), to at least the nearest 1g, of the test portion. Place it, together with

the appropriate ball charge defined in Table 1, in the Los Angeles Machine. Rotate the machine for 500 or 1 000 revolutions as required in Table 1 (Note b).

Pavements & Structures TEST METHOD WA 220.1

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6. At the completion of the test, discharge the entire contents of the drum, taking care to avoid loss, and after removal of the steel balls make a preliminary separation of the test portion on a sieve coarser than a 1.70mm aperture sieve. Following this, sieve the finer fraction on a 1.70mm aperture sieve.

7. Determine the mass of all the sieve fractions. If the difference between the sum of the

masses and the original mass (m1) of the test portion exceeds 0.5 percent of the original mass of the test portion disregard the test and repeat completely using a fresh test portion. Determine the mass, to at least the nearest 1g, of the fraction retained on a 1.70mm aperture sieve.

8. Wash all the material coarser than the 1.70mm aperture sieve by agitation under running

water for approximately ten minutes, dry to constant mass (Note a), in an oven at a temperature within the range of 105°C to 110°C, and cool to room temperature.

9. Resieve the washed and dried material on a 1.70mm aperture sieve and determine the

mass (m2), to at least the nearest 1g, of the fraction retained on the 1.70mm aperture sieve.

10. Repeat Procedure 5 to 9 on at least one further test portion obtained from the same test

sample. CALCULATION 1. Calculate the Los Angeles Abrasion Value of each test, as a percentage, using the formula:

Los Angeles Abrasion = ( )

1

21

mm- m 100

where m1 = original mass of test sample in gram m2 = final mass retained on the 1.70mm aperture sieve in gram 2. Calculate the average Los Angeles Abrasion Value of the two test portions. Where the range of the two values exceeds ten percent of the average value discard the

results and repeat the test. REPORTING Report the average Los Angeles Abrasion Value to the nearest 0.1 percent. NOTES (a) The sample is deemed to be dry when the difference between successive determinations of the mass of the

cooled sample after re-drying, in an oven at a temperature within the range of 105°C to 110°C, for periods of four hours does not exceed 0.1 percent of the original mass of the sample.

Pavements & Structures TEST METHOD WA 220.1

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(b) If so desired, information concerning the presence of soft particles in the test sample may be obtained by determining the loss after a small number of revolutions. In this case care must be taken to avoid loss of any part of the test portion and the entire test portion, including the dust obtained during the test must be returned to the Los Angeles machine for the completion of the test.

Pavements & Structures TEST METHOD WA 220.1

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APPROXIMATE DIMENSIONS

Maximum size of particle

in sample mm

Number

of slots

Internal dimensions

mm

A B C 40 8 45 150 65 20 10 25 125 38 10 12 13 75 29

This design has been found satisfactory but alternative designs may be employed provided that the essential requirements are fulfilled.

FIGURE 1

Pavements & Structures TEST METHOD WA 220.1

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Pavements & Structures TEST METHOD WA 220.1

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